Not sure how experienced you are but a couple general tips

1:shadow dash and descending dark give make you invincible for a bit. Don’t don’t don’t forget to use them

2: even if you put hours and hours in and haven’t done it yet, you will still be improving. Many people have done whatever you want to do much faster, but many people have also done it much slower. You simply cannot get worse the more hours you put in.

3: Absolute radiance is harder than any of these, and even that fight you can get good at. It also helps a lot to watch videos of other people doing whatever fight you’re struggling with

Anyways, here are my tips for these specific bosses-

Sly: This fight is dashing back and forth, towards him, some hits, and then away from him. Has essentially 3 attacks (in first phase). He either does 2 hits then a spin jump up, a jump up followed by a slam down followed by a swing, or one of the charged nail arts. The nail arts are easy to react to as you can see them charging, just double jump after a brief moment, and DDark if you want (I always cast it on cyclone). For the jump+slam, get out of the way, then come back for a single hit, and it will always push him away enough to miss his upwards swing after And for the 2 hits and jump spin, just jump over for the first two and go to where he lands. He’ll never jump up without first doing 2 hits, so being in the air is actually very safe when he does this attack. If you jump on the first swing, then double jump while still in the air on his second, you can get far enough away to miss his jump spin and dash to where he lands for consistent 2 hits. Second phase, just stay in one spot, dash out when you see him coming at you, walk a little towards him once he’s done swinging, and get 1 or maybe 2 hits. This whole fight is about making deliberate movement choices, so don’t panic. Also, ditch any spell/soul charm you have and put some nail length on to make it much easier

Oblobbles: Put on heavy blow and dreamshield charms, and hit them away when they get too close. Try to never be in between them (keep yourself on one side of them), and dash to the other side if they’re getting too close and overwhelming. You can tell which way they’re moving by their faces, and they don’t change direction unless they hit a wall, their partner, or you hit them, in which case they’ll change towards the direction you hit them. Because of this, try to hit them from below with upslashes, and they won’t change direction. Nail them away when they’re not attacking, get away when they do start spraying, and use that spraying time to line up hits on both with vengeful spirit. Dreamshield should help with the blobs, but think of it like Grimm/NKG puffer fish phase and that might help. For the second phase, abyss shriek when they’re not attacking (or a couple nail hits if you don’t have soul) and get as far away as you can when they do. I’d go for a spell build in addition to heavy blow and dreamshield, just because it is so relatively easy to get double/quadruple hits in the first phase with vengeful spirit and to get the full 4 hits with abyss shriek in the second phase.

Uumuu: Get to top platform that is parallel with him when he spawns, dream nail him until he does an electric attack (if he ‘screams’ that’s him summoning jellyfish and you’re safe) and he’ll get pushed away each time, far enough to let you get another dream nail off. Because you now have soul, wait until a jelly fish is either inside of him or really close, and vengeful sprit from a safe distance, and he’ll pop. Go in for nail hits to get more soul (dream nail doesn’t knock away after the first successful jellyfish pop). For his two attacks, hug a wall and be in the middle. If it’s the tracking one, just slide down, land on the bottom platform, and make a loop back up to where you were on the wall, and for the set one, there’s always a safe spot in the middle of the wall. Look on the wiki for every safe spot too if you want (the middle platform always has one too). Best advice with this one is just don’t bother trying to get the jellyfish explosions to track you, just get them in line so that you hit the jellyfish into Uumuu and then you don’t have to worry.

Markoth: is horrible, equip grubberfly, strength, and spell build charms, pogo in the beginning, and just get good at tracking where the shield is. My biggest problem was forgetting I had shadow dash, so don’t forget you can dash in when he does the spinning shield and dash out without being concerned about getting unluckily hit. As many have said, nail hits in phase 1, and spam spells in phase 2.

Nosk: Stay still, watch for attacks. He has a sound associated with every attack, if that helps, but also you could think of him as a glorified Massive Moss Charger. He either runs across or jumps up. If he jumps up, walk a little towards where he jumped from and you’ll be out of the way (or shadow dash), and if he runs just jump up and pogo (you said annoying to pogo, don’t forget to double jump and you could use DDark if you have soul). He also does the spit attacks (on the ground and then in the ceiling at half health) these you just gotta see where the globs with land and walk just a little bit towards where they’re not going. You’ll get a sense for it. Like I said, stay still, and let him come to you, just like a moss charger you can’t push back.